Audio signal processing apparatus

ABSTRACT

In an audio signal processing apparatus for recording a plurality of kinds or systems of audio signals on a recording medium and for reproducing a plurality of kinds or systems of audio signals recorded on the recording medium, in a state where a mixing output mode of mixing the plurality of kinds or systems of audio signals and outputting the mixed audio signals is designated, (i) when a recording operation mode of recording the plurality of kinds or systems of audio signals on the recording medium is designated, the plurality of kinds or systems of audio signals are mixed and outputted while making levels of the plurality of kinds or systems of audio signals equal to each other, and (ii) when a reproducing operation mode of reproducing a plurality of kinds or systems of audio signals recorded on the recording medium is designated, the plurality of kinds or systems of audio signals reproduced from the recording medium are mixed and outputted according to an arbitrarily variable mixing ratio. Thus, the audio signal processing apparatus can record the plurality of kinds or systems of audio signals, effectively utilizing the dynamic range of the recording medium, and can mix and reproduce the plurality of kinds or systems of audio signals in a good reproduction state where S/N is good.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an audio signal processingapparatus for recording a plurality of kinds or a plurality of systemsof audio signals on a recording medium and/or for reproducing aplurality of kinds or a plurality of systems of audio signals recordedon the recording medium.

[0003] 2. Description of Related Art

[0004] At present, there are various audio signal processing apparatusesfor recording a plurality of kinds or a plurality of systems of audiosignals on a recording medium and/or for reproducing a plurality ofkinds or a plurality of systems of audio signals recorded on therecording medium. For example, in the case of a digital video taperecorder (VTR) of the camera-integrated type, a recording formataccording to which a plurality of kinds of audio signals (namely, twosystems of stereophonic audio signals, i.e., a total of four channels ofaudio signals) can be recorded on magnetic tape together with videosignals corresponding to the audio signals, is available.

[0005] Further, considering an apparatus capable of recording aplurality of kinds of audio signals in accordance with theaforementioned recording format, for the purpose of making it possibleto record the aforesaid plurality of kinds of audio signals in a goodS/N condition by effectively utilizing a dynamic range of a magnetictape serving as a recording medium, it is conceivable that the apparatusis provided with a volume for setting a recording level in each channelin such a manner as to optimally adjust the levels of a plurality ofkinds of audio signals (hereinafter, two systems of stereophonic audiosignals will be referred to as “stereophonic-1” signal and“stereophonic-2” signal) when both systems of audio signals are recordedtogether on the magnetic tape. Then, the levels of the plurality ofkinds of audio signals are adjusted by operating the volume, and thelevel-adjusted audio signals are recorded on the magnetic tape.Moreover, when both of the “stereophonic-1” signal and the“stereophonic-2” signal are reproduced together from the magnetic tape,it is conceivable that the apparatus has a mode in which theaforementioned “stereophonic-1” signal and the aforesaid“stereophonic-2” signal are reproduced independently of each other, andanother mode in which the “stereophonic-1” signal and the“stereophonic-2” signal are reproduced while being mixed at an arbitrarymixing ratio which is freely settable.

[0006] However, in the aforementioned apparatus which is provided withthe volume for setting a recording level so as to optimally adjustingthe levels of the “stereophonic-1” and “stereophonic-2” signals forrecording and is capable of recording the “stereophonic-1” and“stereophonic-2” signals while setting the recording levels thereof byusing the volume during recording, and of reproducing the“stereophonic-1” and “stereophonic-2” signals in accordance with themode of mixing the “stereophonic-1” and “stereophonic-2” signals at anarbitrary mixing ratio which is freely settable during reproduction,there arises the following problem. Depending upon a certain manner ofsetting the recording levels of the audio signals by the recording-levelsetting volume, the dynamic range of magnetic tape serving as arecording medium cannot be effectively utilized to record the audiosignals. Moreover, during reproduction, if the “stereophonic-1” and“stereophonic-2” signals are mixed at a desired mixing ratio so as to bereproduced, the state of reproduction results in poor S/N.

BRIEF SUMMARY OF THE INVENTION

[0007] An object of the present invention is to provide an audio signalprocessing apparatus which can solve the aforementioned problems of theconventional apparatus.

[0008] Another object of the present invention is to provide an audiosignal processing apparatus which can record a plurality of kinds ofaudio signals while effectively utilizing the dynamic range of arecording medium and can reproduce a plurality of kinds of audio signalsrecorded on the recording medium, while mixing such audio signals in areproduction state where S/N is good.

[0009] To achieve the above objects, in accordance with an aspect of thepresent invention, there is provided an audio signal processingapparatus for recording a plurality of kinds of audio signals on arecording medium and for reproducing a plurality of kinds of audiosignals recorded on the recording medium, which comprises output modedesignating means, having a selecting output mode of selecting anarbitrary kind of audio signal from among a plurality of kinds of audiosignals and outputting the selected kind of audio signal and a mixingoutput mode of mixing the plurality of kinds of audio signals andoutputting the mixed audio signals, for designating one of the selectingoutput mode and the mixing output mode, operation mode designatingmeans, having a recording operation mode of recording a plurality ofkinds of audio signals on the recording medium and a reproducingoperation mode of reproducing a plurality of kinds of audio signalsrecorded on the recording medium, for designating one of the recordingoperation mode and the reproducing operation mode, and audio signalmixing means for, in a state where the mixing output mode is designatedby the output mode designating means, (i) when the recording operationmode is designated by the operation mode designating means, mixing theplurality of kinds of audio signals while making levels of the pluralityof kinds of audio signals equal to each other, and outputting the mixedaudio signals, and (ii) when the reproducing operation mode isdesignated by the operation mode designating means, mixing the pluralityof kinds of audio signals reproduced from the recording medium accordingto an arbitrarily variable mixing ratio, and outputting the mixed audiosignals.

[0010] Still another object of the present invention is to provide anaudio signal processing apparatus which can record a plurality ofsystems of audio signals by effectively utilizing the dynamic range of arecording medium and can reproduce a plurality of systems of audiosignals recorded on the recording medium, while mixing such audiosignals in a reproduction state where S/N is good.

[0011] To achieve the above objects, in accordance with another aspectof the present invention, there is provided an audio signal processingapparatus for recording a plurality of systems of audio signals on arecording medium and for reproducing a plurality of systems of audiosignals recorded on the recording medium, which comprises output modedesignating means, having a selecting output mode of selecting anarbitrary system of audio signal from among a plurality of systems ofaudio signals and outputting the selected system of audio signal and amixing output mode of mixing the plurality of systems of audio signalsand outputting the mixed audio signals, for designating one of theselecting output mode and the mixing output mode, operation modedesignating means, having a recording operation mode of recording aplurality of systems of audio signals on the recording medium and areproducing operation mode of reproducing a plurality of systems ofaudio signals recorded on the recording medium, for designating one ofthe recording operation mode and the reproducing operation mode, andaudio signal mixing means for, in a state where the mixing output modeis designated by the output mode designating means, (i) when therecording operation mode is designated by the operation mode designatingmeans, mixing the plurality of systems of audio signals while makinglevels of the plurality of systems of audio signals equal to each other,and outputting the mixed audio signals, and (ii) when the reproducingoperation mode is designated by the operation mode designating means,mixing the plurality of systems of audio signals reproduced from therecording medium according to an arbitrarily variable mixing ratio, andoutputting the mixed audio signals.

[0012] Other objects and features of the present invention will becomeapparent from the following detailed description of a preferredembodiment thereof taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0013]FIG. 1 is a block diagram schematically showing the configurationof an audio signal processing apparatus according to an embodiment ofthe present invention.

[0014]FIG. 2 is a diagram for illustrating an operation of adjusting themixing balance in the audio signal processing apparatus shown in FIG. 1.

[0015]FIG. 3 is a flowchart illustrating an operation of the audiosignal processing apparatus shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, a preferred embodiment of the present invention willbe described in detail with reference to the drawings.

[0017] FIGS. 1 to 3 are diagrams for illustrating the embodiment of thepresent invention. FIG. 1 is a block diagram schematically showing theconfiguration of an apparatus for recording two systems of stereophonicaudio signals on a recording medium and for reproducing two systems ofstereophonic audio signals recorded on the recording medium.

[0018] In FIG. 1, reference numeral 1 denotes an input terminal for a“stereophonic-1” audio signal, reference numeral 2 denotes an inputterminal for a “stereophonic-2” audio signal, reference numeral 3denotes a recording level setting circuit for setting a recording levelat which the “stereophonic-1” audio signal is recorded, referencenumeral 4 denotes a recording level setting circuit for setting arecording level at which the “stereophonic-2” audio signal is recorded,reference numeral 5 denotes a recording processing circuit forconverting an input signal into a recording signal form suitable forrecording on the recording medium and for outputting the convertedsignal, reference numeral 6 denotes a recording and reproducing part forrecording a signal on the recording medium, such as magnetic tape or amagnetic disk, and for reproducing a signal recorded on the recordingmedium, reference numeral 7 denotes a reproduction processing circuitfor restoring an original signal from the signal reproduced by therecording and reproducing part 6 and for outputting the restoredoriginal signal, reference numerals 8 and 9 denote output change-overswitches for changing over between outputting of signals which are thesame as the signals supplied to the recording processing circuit 5 andoutputting of signals reproduced by the reproduction processing circuit7 according to whether the apparatus is in the recording operation modeor the reproducing operation mode, reference numeral 10 denotes anoutput level setting circuit for setting an output level at which the“stereophonic-1” audio signal is outputted, reference numeral 11 denotesan output level setting circuit for setting an output level at which the“stereophonic-2” audio signal is outputted, reference numeral 12 denotesa mixing circuit for mixing the “stereophonic-1” audio signal and the“stereophonic-2” audio signal and outputting the mixed signals,reference numeral 13 denotes an output mode selecting switch forselection between an output mode of individually outputting one of the“stereophonic-1” audio signal and the “stereophonic-2” audio signal andanother output mode of mixing the “stereophonic-1” audio signal and the“stereophonic-2” audio signal and outputting the mixed audio signals,reference numeral 14 denotes a monitoring output terminal for outputtingan audio signal to a monitor device, such as a speaker, a headphone anda level meter, and reference numeral 15 denotes a system control circuitfor controlling each of the switches 8, 9 and 10 and the output levelsetting circuits 10 and 11 according to the operation modes.

[0019] Incidentally, although one system of stereophonic audio signal isindicated by a single line in FIG. 1, the constituent elements of theactual apparatus are connected to one another by two cables respectivelycorresponding to audio signals of two channels, namely, the left andright channels Lch and Rch.

[0020] An operation of the audio signal processing apparatus illustratedin FIG. 1 according to the embodiment of the present invention will bedescribed below.

[0021] As shown in FIG. 1, the “stereophonic-1” audio signal and the“stereophonic-2” audio signal are inputted to the input terminals 1 and2, respectively.

[0022] In the recording level setting circuit 3, the recording level ofthe “stereophonic-1” audio signal inputted from the input terminal 1 isset. Further, in the recording level setting circuit 4, the recordinglevel of the “stereophonic-2” audio signal inputted from the inputterminal 2 is set. The audio signals the recording levels of which havebeen set are supplied to the recording processing circuit 5 provided atthe next stage, and are also supplied to terminals R of the outputchange-over switches 8 and 9, respectively, as shown in FIG. 1.

[0023] Then, in the recording processing circuit 5, the “stereophonic-1”audio signal and the “stereophonic-2” audio signal respectivelyoutputted from the recording level setting circuits 3 and 4 areconverted into signals having a recording signal form which is suitablefor recording on the recording medium. Subsequently, the signalsobtained as a result of such a conversion is recorded on the recordingmedium (not shown) in the recording and reproducing part 6.

[0024] On the other hand, in the reproduction processing circuit 7, aprocess which is reverse to the conversion process performed in therecording processing circuit 5 is performed on signals reproduced fromthe recording medium in the recording and reproducing part 6. As aresult, the original “stereophonic-1” and “stereophonic-2” audio signalsare restored from the reproduced signals and are then supplied toterminals P of the output change-over switches 8 and 9, respectively, asshown in FIG. 1.

[0025] Further, in a case where the operation mode of the apparatus isset to the recording operation mode by operating an operation key (notshown), the position of each of the output change-over switches 8 and 9is set to the terminal R thereof in accordance with an instruction orcommand issued from the system control circuit 15, so that signalsoutputted from the recording level setting circuits 3 and 4 are sentalso to the monitoring output terminal 14 through the output levelsetting circuits 10 and 11, the mixing circuit 12 and the output modeselecting switch 13. Accordingly, the user can set the respectiverecording levels at which the “stereophonic-1” and “stereophonic-2”audio signals are recorded, by operating the setting volumesrespectively provided in the recording level setting circuits 3 and 4while monitoring the “stereophonic-1” and “stereophonic-2” audiosignals, which are to be recorded on the recording medium, by means ofthe monitor device, such as a speaker, a headphone or a level meter,connected to the monitoring output terminal 14.

[0026] Incidentally, a signal to be outputted from the monitoring outputterminal 14 to the monitor device (not shown) can be selected by theoutput mode selecting switch 13 in accordance with a selectioninstruction or command which is outputted from the system controlcircuit 15 by operating the operation key (not shown). Thus, a signalselected by the output mode selecting switch 13 is outputted to themonitoring output terminal 14.

[0027] Further, in a case where the operation mode of the apparatus isset to the reproducing operation mode by operating the operation key(not shown), the position of each of the output change-over switches 8and 9 is set to the terminal P thereof in accordance with an instructionor command outputted from the system control circuit 15, so that the“stereophonic-1” and “stereophonic-2” audio signals outputted from thereproduction processing circuit 7 are sent to the monitoring outputterminal 14 through the output level setting circuits 10 and 11, themixing circuit 12 and the output mode selecting switch 13. Accordingly,the user can monitor the “stereophonic-1” and “stereophonic-2” audiosignals, which are recorded on the recording medium, by means of themonitor device, such as a speaker, a headphone or a level meter,connected to the monitoring output terminal 14.

[0028] Incidentally, a signal to be outputted from the monitoring outputterminal 14 to the monitor device (not shown) can be selected by theoutput mode selecting switch 13 in accordance with a selectioninstruction or command which is outputted from the system controlcircuit 15 by operating the operation key (not shown). Similarly as inthe case of the recording operation mode, a signal selected by theoutput mode selecting switch 13 is outputted to the monitoring outputterminal 14.

[0029] In the audio signal processing apparatus according to theembodiment of the present invention, when a “stereophonic-1” or“stereophonic-2” output mode, in which a “stereophonic-1” audio signalor a “stereophonic-2” audio signal is singly outputted, is selected anddesignated by operating the operation key (not shown) as above stated,the system control circuit 15 controls the connection condition of theoutput mode selecting switch 13 according to the designated output mode(namely, when the “stereophonic-1” output mode is designated, the switch13 is set in the position STEREOPHONIC-1 (corresponding to the“stereophonic-1”-side terminal) shown in FIG. 1, and when the“stereophonic-2” output mode is designated, the switch 13 is set in theposition STEREOPHONIC-2 shown in FIG. 1) (in steps S1 and S2 in FIG. 3).Further, in a case where a mixing output mode, in which mixed audiosignals obtained by mixing the “stereophonic-1” and “stereophonic-2”audio signals are outputted, is selected and designated, the output modechange-over switch 13 is set in the position MIXING (corresponding tothe “mixed-output-mode”-side terminal) shown in FIG. 1. An operation ofthe apparatus in the case of selecting the mixing output mode, in whichmixed audio signals obtained by mixing the “stereophonic-1” and“stereophonic-2” audio signals are outputted, will be described below.

[0030] When the mixing output mode is selected and designated, thesystem control circuit 15 controls the signal gain which is set in eachof the output level setting circuits 10 and 11, according to whether theapparatus is operating in accordance with the recording operation modeor the reproducing operation mode.

[0031] Specifically, when the apparatus is operating in accordance withthe recording operation mode, the signal gain which is set in each ofthe output level setting circuits 10 and 11 is so controlled that the“stereophonic-1” audio signal and the “stereophonic-2” audio signal areequally mixed at the mixing circuit 12 and the mixed audio signals areoutputted from the monitoring output terminal 14 (in steps S3 and S4 ofFIG. 3). On the other hand, when the apparatus is operating inaccordance with the reproducing operation mode, the signal gain which isset in each of the output level setting circuits 10 and 11 is socontrolled that the “stereophonic-1” audio signal and the“stereophonic-2” audio signal are mixed at the mixing circuit 12 at amixing ratio corresponding to the mixing balance between the“stereophonic-1” audio signal and the “stereophonic-2” audio signal,which is set by operating the operation key (not shown) (in steps S3 andS5 of FIG. 3).

[0032] As described above, in the audio signal processing apparatusaccording to the embodiment, at the time of reproduction of audiosignals, the user can arbitrarily set the levels of audio signals whichare outputted from the monitoring output terminal 14. For example, in acase where the “stereophonic-2” audio signal is to be supplied to themonitor device in such a manner as to have a high signal level, the“mixing balance” can be set at a value which is at the right-hand sideon the axis of abscissa in the graph of FIG. 2, by operating theoperation key (not shown), so that the signal gain in each of the outputlevel setting circuits 10 and 11 is set in such a manner that the“stereophonic-1” and “stereophonic-2” audio signals are mixed at amixing ratio at which the level of the “stereophonic-1” audio signal islow and the level of the “stereophonic-2” audio signal is high, and themixed audio signals are outputted from the monitoring output terminal14. On the other hand, at the time of recording of audio signals, whenthe user adjusts the recording levels of the “stereophonic-1” audiosignal and the “stereophonic-2” audio signal to be recorded on therecording medium, by operating the setting volume provided in each ofthe recording level setting circuits 3 and 4 while monitoring the“stereophonic-1” audio signal and the “stereophonic-2” audio signal, itis not necessary for the user to adjust the gain in each of the outputlevel setting circuits 10 and 11 in such a manner as to set off therecording levels of the “stereophonic-1” audio signal and the“stereophonic-2” audio signal set at the recording level settingcircuits 3 and 4 so that the balance between the “stereophonic-1” and“stereophonic-2” audio signals which are contained in the mixed audiosignals outputted from the monitoring output terminal 14 is maintained.Thus, in a case where the mixing output mode is selected by operatingthe output mode selecting switch 13, at the time of recording of audiosignals, the output levels of the output level setting circuits 10 and11 are automatically set by the system control circuits 15 in such amanner that the “stereophonic-1” audio signal and the “stereophonic-2”audio signal are outputted always in an equally mixed condition.Accordingly, the user can set optimum recording levels, effectivelyusing the dynamic range of the recording medium, while monitoring themixed audio signals which are obtained by mixing the “stereophonic-1”audio signal and the “stereophonic-2” audio signal. Consequently, S/N ofthe mixed audio signals at the time of reproduction can be enhanced.

[0033] Incidentally, although the embodiment has been described withrespect to two systems of audio signals, the present invention iseffectively applied to audio signal processing apparatuses that processthree or more systems of audio signals.

[0034] As above described, in accordance with the present invention,there is provided an audio signal processing apparatus which can recorda plurality of kinds or a plurality of systems of audio signals,effectively utilizing the dynamic range of the recording medium, and canmix and reproduce a plurality of kinds or a plurality of systems ofaudio signals in a good reproduction state where S/N is good.

[0035] Although the preferred embodiment of the present invention hasbeen described above, it should be understood that the present inventionis not limited thereto and that other modifications will be apparent tothose skilled in the art without departing from the spirit of theinvention.

[0036] The scope of the present invention, therefore, is to bedetermined solely by the appended claims.

1. An audio signal processing apparatus, comprising: (A) input means for inputting a plurality of audio signals; (B) recording/reproducing means for recording the plurality of audio signals input by said input means on a recording medium in a recording mode and for reproducing the plurality of audio signals from the recording medium in a reproducing mode; and (C) audio signal mixing means for automatically mixing the plurality of audio signals input by said input means so as to become a mixing ratio substantially 1:1 in the recording mode, mixing the plurality of audio signals reproduced by said recording/reproducing means in an arbitrary mixing ratio in the reproducing mode, and outputting a mixed audio signal.
 2. An apparatus according to claim 1, wherein said audio signal mixing means outputs the mixed audio signal to an audio monitor.
 3. An apparatus according to claim 1, wherein the plurality of audio signals is composed of two channels of audio signals.
 4. An apparatus according to claim 1, wherein the plurality of audio signals is composed of a stereophonic audio signal.
 5. An apparatus according to claim 1, further comprising: controlling means for controlling a gain of the plurality of audio signals to be mixed by said audio signal mixing means.
 6. An audio signal processing apparatus, comprising: (A) input means for inputting a plurality of audio signals to be recorded on a recording medium, and inputting a plurality of reproduced audio signals reproduced from the recording medium; (B) mixing means for automatically mixing the plurality of audio signals so as to become a mixing ratio substantially 1:1, and mixing the plurality of reproduced audio signals in an arbitrary mixing ratio; and (C) output means for outputting a mixed audio signal mixed by said mixing means to an audio monitor.
 7. An apparatus according to claim 6, wherein the plurality of audio signals is composed of two channels of audio signals.
 8. An apparatus according to claim 6, wherein the plurality of audio signals is composed of a stereophonic audio signal.
 9. An apparatus according to claim 6, further comprising: controlling means for controlling a gain of the plurality of audio signals and the plurality of reproduced audio signals to be mixed by said mixing means.
 10. An audio signal processing apparatus, comprising: (A) input circuit inputs a plurality of audio signals; (B) recording/reproducing device records the plurality of audio signals input by said input circuit on a recording medium in a recording mode and reproduces the plurality of audio signals from the recording medium in a reproducing mode; (C) audio signal mixing circuit, which is connected to said input circuit and said recording/reproducing device, automatically mixes the plurality of audio signals input by said input circuit so as to become a mixing ratio substantially 1:1 in the recording mode, and mixes the plurality of audio signals reproduced by said recording/reproducing device in an arbitrary mixing ratio in the reproducing mode; and (D) output circuit, which is connected to said audio signal mixing circuit, outputs a mixed audio signal mixed by said audio signal mixing circuit.
 11. An audio signal processing apparatus, comprising: (A) input circuit inputs a plurality of audio signals to be recorded on a recording medium, and inputs a plurality of reproduced audio signals reproduced from the recording medium; (B) mixing circuit, which is connected to said input circuit, automatically mixes the plurality of audio signals so as to become a mixing ratio substantially 1:1, and mixes the plurality of reproduced audio signals in an arbitrary mixing ratio; and (C) output circuit, which is connected to said mixing circuit, outputs a mixed audio signals mixed by said mixing circuit to an audio monitor. 